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Local Memory
MCF5272 ColdFire
®
Integrated Microprocessor User’s Manual, Rev. 3
4-12
Freescale Semiconductor
4.5.3
Instruction Cache Programming Model
Three supervisor registers define the operation of the instruction cache and local bus controller: the cache
control register (CACR) and two access control registers (ACR0, ACR1).
map of the CACR and ACRs. These registers have the following characteristics:
•
The CACR and ACRs can be accessed only in supervisor mode using the MOVEC instruction with
an Rc value of 0x002 (CACR), 0x004 (ACR0), and 0x005 (ACR1).
•
Addresses not assigned to the registers and undefined register bits are reserved for future
expansion. Write accesses to these reserved address spaces and reserved register bits have no
effect; read accesses return zeros.
•
The reset value column indicates the initial value of the register at reset. Uninitialized fields may
contain random values after reset.
•
The access column indicates whether the corresponding register can be read, written or both.
Attempts to read a write-only register cause zeros to be returned. Attempts to write to a read-only
register are ignored.
4.5.3.1
Cache Control Register (CACR)
The CACR controls operation of the instruction cache. It provides a set of default memory access attributes
for when a reference address does not map into spaces defined by the ACRs. The supervisor-level CACR
is accessed in the CPU address space using the MOVEC instruction with an Rc encoding of 0x002. The
CACR can be read or written when the processor is in background debug mode (BDM).
Table 4-7. Memory Map of Instruction Cache Registers
Address (using MOVEC)
Name
Width
Description
Reset Value
0x002
CACR
32
Cache control register
0x0000
0x004
ACR0
32
Access control register 0
0x0000
0x005
ACR1
32
Access control register 1
0x0000
31
30
29
28
27
26
25
24
23
16
Field CENB
—
CDPI CFRZ
—
CINVA
—
Reset
0000_0000_0000_0000
R/W
Write (R/W by debug module)
15
10
9
8
7
6
5
4
2
1
0
Field
—
CEIB DCM DBWE
—
DWP
—
CLNF
Reset
0000_0000_0000_0000
R/W
Write (R/W by debug module)
Rc
0x002
Figure 4-4. Cache Control Register (CACR)